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I am sorry, "AEST" was wrong. I can't work out what timezone code it is, but
my default timezone here in eastern australia prints as:
> as.POSIXct("1970-01-01", tz="")
[1] "1970-01-01 AUS Eastern Daylight Time"
and that is the one that has repeated dates before 1970.
But I take your point that it is fundamentally a problem with Windows.
--Felix
On 3/19/07, Prof Brian Ripley <[EMAIL PROTECTED]> wrote:
>
> Hmm, AEST is not a valid time zone on Windows.
> See ?as.POSIXlt for one of several places where this is documented.
>
> But in any case, the underlying problem is in the OS, and we only try to
> work around it to the best of our knowledge (and that excludes
> undocumented time zones).
>
>
> On Mon, 19 Mar 2007, [EMAIL PROTECTED] wrote:
>
> > Times from seq.POSIXt come out wrong in AEST timezone around Feb 29
> every
> > leap year before 1970 (on Windows XP).
> >
> > According to help(DateTimeClasses), this is handled by "our own C code".
> >
> >> x <- as.POSIXct("1968-02-27") # tz="AEST"
> >> x.gmt <- as.POSIXct("1968-02-27", tz="GMT")
> >> data.frame(
> > GMT=seq(x.gmt, by="day", length=8),
> > byday=seq(x, by="day", length=8),
> > byDST=seq(x, by="DSTday", length=8))
> > GMT byday byDST
> > 1 1968-02-27 1968-02-27 1968-02-27
> > 2 1968-02-28 1968-02-28 1968-02-28
> > 3 1968-02-29 1968-03-01 1968-03-02
> > 4 1968-03-01 1968-03-02 1968-03-02
> > 5 1968-03-02 1968-03-02 1968-03-02
> > 6 1968-03-03 1968-03-03 1968-03-03
> > 7 1968-03-04 1968-03-04 1968-03-04
> > 8 1968-03-05 1968-03-05 1968-03-05
> >
> >> R.version
> > _
> > platform i386-pc-mingw32
> > arch i386
> > os mingw32
> > system i386, mingw32
> > status
> > major 2
> > minor 4.1
> > year 2006
> > month 12
> > day 18
> > svn rev 40228
> > language R
> > version.string R version 2.4.1 (2006-12-18)
> >
> >
> >
> >
>
> --
> Brian D. Ripley, [EMAIL PROTECTED]
> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
> University of Oxford, Tel: +44 1865 272861 (self)
> 1 South Parks Road, +44 1865 272866 (PA)
> Oxford OX1 3TG, UK Fax: +44 1865 272595
>
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I am sorry, "AEST" was wrong. I can't work out what timezone code
it is, but my default timezone here in eastern australia prints as:<br>>
as.POSIXct("1970-01-01", tz="")<br>[1] "1970-01-01 AUS
Eastern Daylight Time"
<br><br>and that is the one that has repeated dates before 1970.<br><br>But I
take your point that it is fundamentally a problem with
Windows.<br><br>--Felix<br><br><br><div><span class="gmail_quote">On 3/19/07,
<b class="gmail_sendername">
Prof Brian Ripley</b> <<a href="mailto:[EMAIL PROTECTED]">[EMAIL
PROTECTED]</a>> wrote:</span><blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex;
padding-left: 1ex;">
Hmm, AEST is not a valid time zone on Windows.<br>See ?as.POSIXlt for one of
several places where this is documented.<br><br>But in any case, the underlying
problem is in the OS, and we only try to<br>work around it to the best of our
knowledge (and that excludes
<br>undocumented time zones).<br><br><br>On Mon, 19 Mar 2007, <a
href="mailto:[EMAIL PROTECTED]">[EMAIL PROTECTED]</a> wrote:<br><br>> Times
from seq.POSIXt come out wrong in AEST timezone around Feb 29 every<br>>
leap year before 1970 (on Windows XP).
<br>><br>> According to help(DateTimeClasses), this is handled by
"our own C code".<br>><br>>> x <-
as.POSIXct("1968-02-27") # tz="AEST"<br>>> x.gmt
<- as.POSIXct("1968-02-27", tz="GMT")
<br>>> data.frame(<br>> GMT=seq(x.gmt,
by="day", length=8),<br>> byday=seq(x,
by="day", length=8),<br>> byDST=seq(x,
by="DSTday",
length=8))<br>>
GMT byday byDST
<br>> 1 1968-02-27 1968-02-27 1968-02-27<br>> 2 1968-02-28 1968-02-28
1968-02-28<br>> 3 1968-02-29 1968-03-01 1968-03-02<br>> 4 1968-03-01
1968-03-02 1968-03-02<br>> 5 1968-03-02 1968-03-02 1968-03-02<br>> 6
1968-03-03 1968-03-03 1968-03-03
<br>> 7 1968-03-04 1968-03-04 1968-03-04<br>> 8 1968-03-05 1968-03-05
1968-03-05<br>><br>>>
R.version<br>>
_<br>> platform i386-pc-mingw32<br>>
arch i386<br>>
os
mingw32
<br>> system i386,
mingw32<br>> status<br>>
major 2<br>>
minor 4.1<br>>
year 2006<br>>
month 12<br>>
day 18<br>>
svn rev 40228<br>>
language R
<br>> version.string R version 2.4.1
(2006-12-18)<br>><br>><br>><br>><br><br>--<br>Brian D.
Ripley, <a
href="mailto:[EMAIL PROTECTED]">[EMAIL PROTECTED]</a><br>Professor of Applied
Statistics,
<a
href="http://www.stats.ox.ac.uk/~ripley/";>http://www.stats.ox.ac.uk/~ripley/</a><br>University
of
Oxford,
Tel: +44 1865 272861 (self)<br>1 South Parks
Road,
+44 1865 272866 (PA)<br>Oxford OX1 3TG,
UK Fax: +44
1865 272595
<br></blockquote></div><br><br>
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